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Handbook of Experimental Pharmacology 2017Myosins are cytoskeletal motor proteins that use energy derived from ATP hydrolysis to generate force and movement along actin filaments. Humans express 38 myosin genes... (Review)
Review
Myosins are cytoskeletal motor proteins that use energy derived from ATP hydrolysis to generate force and movement along actin filaments. Humans express 38 myosin genes belonging to 12 classes that participate in a diverse range of crucial activities, including muscle contraction, intracellular trafficking, cell division, motility, actin cytoskeletal organisation and cell signalling. Myosin malfunction has been implicated a variety of disorders including deafness, hypertrophic cardiomyopathy, Usher syndrome, Griscelli syndrome and cancer. In this chapter, we will first discuss the key structural and kinetic features that are conserved across the myosin family. Thereafter, we summarise for each member in turn its unique functional and structural adaptations, cellular roles and associated pathologies. Finally, we address the broad therapeutic potential for pharmacological interventions that target myosin family members.
Topics: Animals; Humans; Movement; Myosins; Protein Domains
PubMed: 27757761
DOI: 10.1007/164_2016_29 -
Proceedings of the National Academy of... Oct 2022The major cytoskeleton protein actin undergoes cyclic transitions between the monomeric G-form and the filamentous F-form, which drive organelle transport and cell...
The major cytoskeleton protein actin undergoes cyclic transitions between the monomeric G-form and the filamentous F-form, which drive organelle transport and cell motility. This mechanical work is driven by the ATPase activity at the catalytic site in the F-form. For deeper understanding of the actin cellular functions, the reaction mechanism must be elucidated. Here, we show that a single actin molecule is trapped in the F-form by fragmin domain-1 binding and present their crystal structures in the ATP analog-, ADP-Pi-, and ADP-bound forms, at 1.15-Å resolutions. The G-to-F conformational transition shifts the side chains of Gln137 and His161, which relocate four water molecules including W1 (attacking water) and W2 (helping water) to facilitate the hydrolysis. By applying quantum mechanics/molecular mechanics calculations to the structures, we have revealed a consistent and comprehensive reaction path of ATP hydrolysis by the F-form actin. The reaction path consists of four steps: 1) W1 and W2 rotations; 2) P-O bond cleavage; 3) four concomitant events: W1-PO formation, OH and proton cleavage, nucleophilic attack by the OH against P, and the abstracted proton transfer; and 4) proton relocation that stabilizes the ADP-Pi-bound F-form actin. The mechanism explains the slow rate of ATP hydrolysis by actin and the irreversibility of the hydrolysis reaction. While the catalytic strategy of actin ATP hydrolysis is essentially the same as those of motor proteins like myosin, the process after the hydrolysis is distinct and discussed in terms of Pi release, F-form destabilization, and global conformational changes.
Topics: Actins; Adenosine Diphosphate; Adenosine Triphosphate; Dalteparin; Hydrolysis; Myosins; Protons; Water
PubMed: 36252034
DOI: 10.1073/pnas.2122641119 -
Cell Reports. Medicine May 2024Pathogenic variants in MYH7 and MYBPC3 account for the majority of hypertrophic cardiomyopathy (HCM). Targeted drugs like myosin ATPase inhibitors have not been...
Pathogenic variants in MYH7 and MYBPC3 account for the majority of hypertrophic cardiomyopathy (HCM). Targeted drugs like myosin ATPase inhibitors have not been evaluated in children. We generate patient and variant-corrected iPSC-cardiomyocytes (CMs) from pediatric HCM patients harboring single variants in MYH7 (V606M; R453C), MYBPC3 (G148R) or digenic variants (MYBPC3 P955fs, TNNI3 A157V). We also generate CMs harboring MYBPC3 mono- and biallelic variants using CRISPR editing of a healthy control. Compared with isogenic and healthy controls, variant-positive CMs show sarcomere disorganization, higher contractility, calcium transients, and ATPase activity. However, only MYH7 and biallelic MYBPC3 variant-positive CMs show stronger myosin-actin binding. Targeted myosin ATPase inhibitors show complete rescue of the phenotype in variant-positive CMs and in cardiac Biowires to mirror isogenic controls. The response is superior to verapamil or metoprolol. Myosin inhibitors can be effective in genotypically diverse HCM highlighting the need for myosin inhibitor drug trials in pediatric HCM.
Topics: Humans; Induced Pluripotent Stem Cells; Cardiomyopathy, Hypertrophic; Cardiac Myosins; Child; Myocytes, Cardiac; Myosin Heavy Chains; Carrier Proteins; Genotype; Myosins; Male; Female; Sarcomeres
PubMed: 38642550
DOI: 10.1016/j.xcrm.2024.101520 -
Cells Feb 2024Parenchyma of pulmonary cancers acquires contractile properties that resemble those of muscles but presents some particularities. These non-muscle contractile tissues...
Parenchyma of pulmonary cancers acquires contractile properties that resemble those of muscles but presents some particularities. These non-muscle contractile tissues could be stimulated either electrically or chemically (KCl). They present the Frank-Starling mechanism, the Hill hyperbolic tension-velocity relationship, and the tridimensional time-independent tension-velocity-length relationship. Relaxation could be obtained by the inhibition of crossbridge molecular motors or by a decrease in the intracellular calcium concentration. They differ from muscles in that their kinetics are ultraslow as evidenced by their low shortening velocity and myosin ATPase activity. Contractility is generated by non-muscle myosin type II A and II B. The activation of the β-catenin/WNT pathway is accompanied by the high level of the non-muscle myosin observed in lung cancers.
Topics: Humans; Myosins; Lung Neoplasms; Muscle Contraction; Muscles
PubMed: 38474391
DOI: 10.3390/cells13050427 -
The Journal of Biological Chemistry Aug 2023Myosin-1D (myo1D) is important for Drosophila left-right asymmetry, and its effects are modulated by myosin-1C (myo1C). De novo expression of these myosins in nonchiral...
Myosin-1D (myo1D) is important for Drosophila left-right asymmetry, and its effects are modulated by myosin-1C (myo1C). De novo expression of these myosins in nonchiral Drosophila tissues promotes cell and tissue chirality, with handedness depending on the paralog expressed. Remarkably, the identity of the motor domain determines the direction of organ chirality, rather than the regulatory or tail domains. Myo1D, but not myo1C, propels actin filaments in leftward circles in in vitro experiments, but it is not known if this property contributes to establishing cell and organ chirality. To further explore if there are differences in the mechanochemistry of these motors, we determined the ATPase mechanisms of myo1C and myo1D. We found that myo1D has a 12.5-fold higher actin-activated steady-state ATPase rate, and transient kinetic experiments revealed myo1D has an 8-fold higher MgADP release rate compared to myo1C. Actin-activated phosphate release is rate limiting for myo1C, whereas MgADP release is the rate-limiting step for myo1D. Notably, both myosins have among the tightest MgADP affinities measured for any myosin. Consistent with ATPase kinetics, myo1D propels actin filaments at higher speeds compared to myo1C in in vitro gliding assays. Finally, we tested the ability of both paralogs to transport 50 nm unilamellar vesicles along immobilized actin filaments and found robust transport by myo1D and actin binding but no transport by myo1C. Our findings support a model where myo1C is a slow transporter with long-lived actin attachments, whereas myo1D has kinetic properties associated with a transport motor.
Topics: Animals; Actins; Kinetics; Myosin Type I; Drosophila Proteins; Protein Domains; Drosophila melanogaster; Functional Laterality
PubMed: 37380077
DOI: 10.1016/j.jbc.2023.104961 -
Bioorganic & Medicinal Chemistry Jan 2021The interaction of actin and myosin is essential for cell migration. We have identified kaempferol and pentahalogenated pseudilins as efficient inhibitors of migration...
The interaction of actin and myosin is essential for cell migration. We have identified kaempferol and pentahalogenated pseudilins as efficient inhibitors of migration of MDA-MB-231 breast adenocarcinoma cells. The compounds were studied with respect to possible effects on myosin-2-ATPase activity. The pentahalogenated pseudilins inhibited the enzyme activity in vitro. Flavonoids showed no effect on enzyme activity. The polymerization dynamics of actin was measured to test whether the integrity of F-actin is essential for the migration of MDA-MB-231 cells. Quercetin and kaempferol depolymerized F-actin with similar efficiencies as found for the pentahalogenated pseudilins, whereas epigallocatechin showed the weakest effect. As the inhibitory effect on cell migration may be caused by a toxic effect, we have performed a cytotoxicity test and, furthermore, investigated the influence of the test compounds on cardiac function in eleutheroembryos of medaka (Oryzias latipes). Compared with the pentahalogenated pseudilins, the cytotoxic and cardiotoxic effects of flavonoids on medaka embryos were found to be moderate.
Topics: Actins; Cell Movement; Cell Survival; Dose-Response Relationship, Drug; Humans; Kaempferols; Molecular Structure; Myosins; Quercetin; Structure-Activity Relationship; Tumor Cells, Cultured
PubMed: 33341499
DOI: 10.1016/j.bmc.2020.115928 -
International Journal of Molecular... Jun 2023The binding of calcium and magnesium ions to proteins is crucial for regulating heart contraction. However, other divalent cations, including xenobiotics, can accumulate... (Review)
Review
The binding of calcium and magnesium ions to proteins is crucial for regulating heart contraction. However, other divalent cations, including xenobiotics, can accumulate in the myocardium and enter cardiomyocytes, where they can bind to proteins. In this article, we summarized the impact of these cations on myosin ATPase activity and EF-hand proteins, with special attention given to toxic cations. Optimal binding to EF-hand proteins occurs at an ionic radius close to that of Mg and Ca. In skeletal Troponin C, Cd, Sr, Pb, Mn, Co, Ni, Ba, Mg, Zn, and trivalent lanthanides can substitute for Ca. As myosin ATPase is not a specific MgATPase, Ca, Fe, Mn, Ni, and Sr could support myosin ATPase activity. On the other hand, Zn and Cu significantly inhibit ATPase activity. The affinity to various divalent cations depends on certain proteins or their isoforms and can alter with amino acid substitution and post-translational modification. Cardiac EF-hand proteins and the myosin ATP-binding pocket are potential molecular targets for toxic cations, which could significantly alter the mechanical characteristics of the heart muscle at the molecular level.
Topics: Cations, Divalent; Contractile Proteins; Heart; Myosins; Cations; Calcium
PubMed: 37445756
DOI: 10.3390/ijms241310579 -
Cellular and Molecular Life Sciences :... Jun 2024Members of the myosin superfamily of molecular motors are large mechanochemical ATPases that are implicated in an ever-expanding array of cellular functions. This review... (Review)
Review
Members of the myosin superfamily of molecular motors are large mechanochemical ATPases that are implicated in an ever-expanding array of cellular functions. This review focuses on mammalian nonmuscle myosin-2 (NM2) paralogs, ubiquitous members of the myosin-2 family of filament-forming motors. Through the conversion of chemical energy into mechanical work, NM2 paralogs remodel and shape cells and tissues. This process is tightly controlled in time and space by numerous synergetic regulation mechanisms to meet cellular demands. We review how recent advances in structural biology together with elegant biophysical and cell biological approaches have contributed to our understanding of the shared and unique mechanisms of NM2 paralogs as they relate to their kinetics, regulation, assembly, and cellular function.
Topics: Animals; Humans; Myosins; Models, Molecular
PubMed: 38878079
DOI: 10.1007/s00018-024-05264-6 -
Current Biology : CB Feb 2017Stimulated by our 2015 Current Biology paper [1], Zambon et al. reinvestigated how three myosin isoforms participate in the formation and constriction of the contractile...
Stimulated by our 2015 Current Biology paper [1], Zambon et al. reinvestigated how three myosin isoforms participate in the formation and constriction of the contractile ring in fission yeast. Our paper presented evidence that these myosin isoforms have distinct roles: "Conventional myosin-II Myo2 is crucial to ring assembly, unconventional myosin-II Myp2 is most important for ring constriction, and type V myosin Myo51 aids the other two myosins." Zambon et al. used different markers to reexamine the contributions of the three myosins to cytokinesis and concluded "that Myo2p is the major motor involved in ring contraction in S. pombe." Here, we show that most of the differences observed by Zambon et al. can be attributed to their use of the Rlc1p-3GFP marker, which genetically interacts with myo2-E1.
Topics: Constriction; Myosin Heavy Chains; Myosin Type II; Myosins; Schizosaccharomyces; Schizosaccharomyces pombe Proteins
PubMed: 28171751
DOI: 10.1016/j.cub.2016.12.025 -
The Journal of Biological Chemistry Jul 2022The myosin II motors are ATP-powered force-generating machines driving cardiac and muscle contraction. Myosin II heavy chain isoform-beta (β-MyHC) is primarily...
The myosin II motors are ATP-powered force-generating machines driving cardiac and muscle contraction. Myosin II heavy chain isoform-beta (β-MyHC) is primarily expressed in the ventricular myocardium and in slow-twitch muscle fibers, such as M. soleus. M. soleus-derived myosin II (SolM-II) is often used as an alternative to the ventricular β-cardiac myosin (βM-II); however, the direct assessment of biochemical and mechanical features of the native myosins is limited. By employing optical trapping, we examined the mechanochemical properties of native myosins isolated from the rabbit heart ventricle and soleus muscles at the single-molecule level. We found purified motors from the two tissue sources, despite expressing the same MyHC isoform, displayed distinct motile and ATPase kinetic properties. We demonstrate βM-II was approximately threefold faster in the actin filament-gliding assay than SolM-II. The maximum actomyosin (AM) detachment rate derived in single-molecule assays was also approximately threefold higher in βM-II, while the power stroke size and stiffness of the "AM rigor" crossbridge for both myosins were comparable. Our analysis revealed a higher AM detachment rate for βM-II, corresponding to the enhanced ADP release rates from the crossbridge, likely responsible for the observed differences in the motility driven by these myosins. Finally, we observed a distinct myosin light chain 1 isoform (MLC1sa) that associates with SolM-II, which might contribute to the observed kinetics differences between βM-II and SolM-II. These results have important implications for the choice of tissue sources and justify prerequisites for the correct myosin heavy and light chains to study cardiomyopathies.
Topics: Animals; Cardiac Myosins; Heart Ventricles; Myosin Heavy Chains; Myosin Type II; Myosins; Protein Isoforms; Rabbits; Ventricular Myosins
PubMed: 35623390
DOI: 10.1016/j.jbc.2022.102070